Corner locking construction for paperboard containers



Oct. 30, 1951 R. E. ACKER 2,573,379

CORNER LOCKING CONSTRUCTION FOR PAPERBOARD CONTAINERS Filed Nov. 29, 1947 3 Sheets-Sheet l zgzw w Oct. 30, 1951 R. E.VACKER 2,573,379

CORNER LOCKING cons'mucnon FOR PAPERBOARD CONTAINERS Filed Nov. 29, 1947 v s Sheets-Sheet 2 R. E. ACKER Oct. 30, 1951 CORNER LOCKING CONSTRUCTION FOR PAPERBOARD CONTAINERS s Sheefs-Sheet 3 Bag,

Filed Nov. 29, 1947 Patented Oct. 30, 1951 CORNER LOCKING CONSTRUCTION FOR PAPERBOARD CONTAINERS Ralph E. Acker, Fort Worth, Tex., assignor to Container Corporation of America, Chicago,

111., a corporation of Delaware Application November 29, 1947, Serial No. 788,789

3 Claims. (Cl. 229-32) This invention relates to a paperboard container of the tray type adapted to be readily erected from a blank and provided with corner locking means which look the walls in containerforining relation upon positioning of the walls in erected condition. More particularly, the invention relates to a corner locking construction for a paperboard container automatically effectlve upon setting up of the container.

Briefly and generally stated, the invention is embodied in a container having locking tabs on opposite ends of each of one pair of wall members, and slits between adjacent wall members in which the tabs lockingly engage to retain the several wall members in desired trihedral relation to form the corners of the container. The principle of the invention is applicable to many types of containers with wall members in various relations to each other.

It is an object of the invention to provide a paperboard container in which the ends of adjacent wall elements are locked in set up position by cooperating locking means operable simply by movement of the wall elements into position. It is another object to provide a corner locking construction for a paperboard container which is efiective automatically upon movement of the container wall members to erected position to lock said members in the erected position. It is also an object to provide a corner lock construction for a paperboard container which will automatically lock the wall members of the container in desired trihedral relation. A further object is to provide a corner lock arrangement for rectangular containers which will retain the walls in desired squared relation. Still another object is the provision of a container in which adjacent wall elements are provided with cooperable locking means at their contiguous portions in such relation that they coact to lock the wall elements in predetermined erected po'sition automatically upon movement of the wall elements to said position. A still further object of the invention is to provide a blank which may readily be folded to form a container with such a corner locking construction.

Other and further objects and features of the invention will be apparent to those skilled in the art from the following description and the appended drawings, which form a part thereof.

Figure 1 is a plan of the blank for one embodiment of my invention;

Figure 2 is a perspective view of the blank of Figure 1 in partially erected condition, different 2 stages in the setting up of the container being shown at opposite ends;

Figure 3 illustrates the container with one end in the final setting up stage and the other end fully set up;

Figure 4 is a plan of a blank for another embodiment of my invention;

Figure 5 is a fragmentary perspective view of a portion of the blank of Figure 4 in partially erected condition;

Figure 6 i a perspective view of one end of a container erected from the blank of Figure 4;

Figure 7 is a plan of a blank for still another embodiment of my invention; and

Figure 8 is a perspective view of one end of a container formed from the blank shown in Figure '7.

Referring to Figure 1, the blank Ill comprises a sheet of paperboard with parallel longitudinal score lines II and transverse parallel score lines I2 perpendicular to lines II defining a bottom panel 13. Side wall panels I4 and end wall panels I5 are hinged to the bottom panel I3 along the lines II and I2, respectively, the ends of the panels I4 being substantially aligned with the lines I2 and the ends of the panels I5 substantially aligned with the lines II. Corner sections I6 each extending between the ends of adjacent panels I4 and I5 are each divided into a locking tab I1 and an end flap I8.

Each tab I1 is hinged along line Ila to an end edge of the end panel i5 and is divided from the end of the side panel I4 by a cut l9 along the side panel end. The tab is divided from the flap I8 by a cut 20 which extends from a point adjacent the outer end of the hinge line Ila to an intermediate point of the cut I9. As shown in Figure 1, this cut 20 conforms to an arc with a radius and center such that the dimension of the tab along the hinge line is greater than its dimension along the cut I9. The hinge line Ila is preferably oflset somewhat inwardly of the score line H, as shown. Each flap I8 is hinged to the portion of the end of the panel I4 which extend between the outer end of the cut I9 and the outer margin of said panel, but has an edge portion extending from the outer end of the cut I9 to its intersection with the cut 20. The portion of the cut I9 extending outwardly beyond this intersection provides a slit, designated 2I, between the flap I8 and a portion of the end edge of the panel I4. The flap I8 is separated from the end panel I5 by a cut 22 extending from the margin of the blank to the outer end of and intersecting the cut 20. A cut 23 extends from the intersection of cuts 23 and $22 to the outer end of the hinge line Ila. The cut 23 is of such shape and direction that a notch 2d, best shown at the left end of Figure 3, is provided thereby when the tab 11 is bent perpendicularly to the end panel I5 along the hinge line 81a. The notch and the outer end of the slit 2|, or cut l9, are spaced substantially the same distance from the adjacent corner of the bottom panel I3.

The container may be set up by folding the various elements as clearly illustrated in Fig ures 2 and 3. The flaps l8 may first be bent upwardly perpendicular to the side panels 14, along the hinge connections described, as shown at the right in Figure 2, and the side panels H are then bent upwardly along the lines H into perpendicular relation to the bottom panel l3, as shown at the left in Figure 2. As will be clear from the drawing, this positioning of the side panels l4 brings the end flaps I8 into position between the panels l4 at each end in a plane substantially parallel to the plane of the end wall panel l5 when the latter is moved to set up position.

The tabs II are then bent along their hinge lines into substantially perpendicular relation with the end wall panels l5, and the panels i5 swung upwardly on the lines l2, with the tabs l'l engaging the inner surfaces of the side wall panels M. The described offsetting of the hinge lines 17a facilitates this positioning of the tabs relative to the side wall panels, as well as their subsequent movement to locking position. This stage in the erection of the container is shown at the left end of Figure 3. As movement of the panels ii to the perpendicular position continues, the tabs I1 engage in the slits 2 I, and due to the greater dimension of the tab along its hinge line as described above and the formation of the slit 2| so that its closed end is substantially the same distance from the adjacent corner of the bottom panel 13 as the notch 24, the engagement of the tab in the slit increases until the notch lockingly engages the closed end of the slit. This locking action occurs when the panel [5 reaches its position perpendicular to the bottom panel. The tabs l1 and flaps l8 will then be in crossing relation to each other, with the tabs l1 lying parallel to the side panels 14 in face to face relation and the flaps 18 extending parallel to the panels l5 also in face to face relation.

The engagement of the notch 24 with the closed end of the slit 2| holds the end panel from moving out of its perpendicular relation with the bottom panel, and the engagement of the tab 11 in the slit 2| prevents similar movement of the side panel H. The locked set up condition of the parts is shown clearly at the right in Figure 3.

The flaps 18 are shown as so shaped and dimensioned that the two flaps at each end of the box will abut each other and engage the crease at the bottom of the end panel. This counteracts any tendency the flaps may have to spring upwardly due to the resilience of the container material, and gives increased strength and rigidity to the container. This is not a necessary structural feature of the invention, however, and the flaps may be otherwise shaped and dimensioned than as shown and described. Similarly, the tabs I! need not be of the exact shape and dimensions shown and described, the two essentials being that the edge defined by the cut 28 have no point at a greater distance from the adjacent corner of the panel l3 than the distance of the notch 24 from that corner, and that sumcieut material be provided at the locking or notch end of the tab to prevent easy yielding of the lock.

If desired, particularly where relatively thick paperboard is employed as the container material, certain of the cuts and hinge lines besides the lines Ha may be offset in relation to each other so as to allow for the thickness of the paperboard in forming the corners of the container. Such ofisetting is shown in the modification illustrated in Figures 6 and 7 and described in connection with those figures.

In setting up the blank into container form, the particular order of folding the various parts as described above need not be followed, since the only necessary sequence in the folding steps is that the end panels It be folded on the lines 12 after the other elements have been folded, in any desired order, to substantially the positions shown at the left in FigureB. For example, it may be more convenient to fold the side wall panels l4 and the tabs H on the lines fl 'and Ho, respectively, as the first folding step. then fold the flaps [8 about their hinge lines as a second step, and finally swing position. I

If it is desired to fold the tabs l1 and the side wall panels I4 in one step, whether it be the first or a later folding step, a readily breakable con.- nection may be left bridging the cut lrbetween the tabs II and panel 14, preferably nearer the out 2|! than the hinge line 11a. Such a connection is not shown in the form of container illustrated in Figures 1 to 3, but a somewhat similar connection is illustrated in Figures 4 and 5, although for a somewhat different purpose.

Referring to the modified embodiment of the invention illustrated in Figures 4 to 6 inclusive, the blank 30 comprises a sheet with parallel longitudinal score lines 3| and parallel transverse score lines 32 defining a substantially rectangular bottom panel 33. Hinged to the bottom panel along the lines 3| and 32 are side wall elements 34 and end walls 35, respectively. Hinged to the ends of the end wall panels 35 along lines 38 substantially perpendicular to the lines 32 are end wall elements 31. The lines 36 may be aligned with the lines 3|, as shown, or may be offset somewhat outwardly thereof. Hinged on the elements 31 along lines 38 which extend substantially perpendicular to the lines 36 and are preferably offset outwardly relative to the lines 32 are look tabs 38. These tabs may be substantially similar to the lock tab H of the previously described form of the invention. A cut 40 extends from the hinge line 38 of each tab along the line 3| to separate the tab from the bottom panel 33, the length of this out being approximately equal to the length of the hinge line 38, and somewhat less than the greatest dimension of the tab 39 in the direction perpendicular to the line 3|. A cut 4| is provided at the end of the tab adjacent the outer end of the hinge line 38, this cut extending from this end of the line 38 to the edge of the tab, and serving to provide a notch 45, best shown in Figure 6, when the tab 39 is bent on its hinge line. The tab 39 and side wall element 34 are formed from the portion of the blank defined by two parallel hinge lines 38, the adjacent line 3| and the margin of the blank. The tab 38 is separated from the adjacent edge of the side wall element 34 by a cut 42 which extends from the outer end of the cut H to a point closely adjacent a point intermediate the length of the cut 40. The cut 42 does not quite intersect the cut 48, so as to leave a slight readily breakable the panels 53 into th erect I connection 43 between the tab 33 and the wall element 34 at what becomes the bottom of the element 34 when it is in erected position. Of course, the cut 42 may intersect the cut 43, and the connection 43 may bridge cut 42 at a point close to cut 40, but the location of the connection as shown is preferred. The portion of the cut 40 extending inwardly beyond the connection 43 provides a slit between the element 34 and the bottom panel 33. The cut 42 is shown as arcuate and substantially similar to the cut 23 of the previously described form of the invention, and may, of course, have a shape other than arcuate. As illustrated, the outer marginal portion of the element 34 at each end is cut away so as to terminate at aninterme'diate point of the cut 42, and short of the cut 4|. A portion of the edge of the tab 39 defined by the out 42 thus constitutes a portion of the margin of the blank. It will be clear, however, that this particular shape of the side wall element 34 is not a necessary feature of the invention, and that it might be otherwise formed thanas shown.

In forming the blank into a container, the side wall elements are first bent on the lines 3| into perpendicular relation with the bottom panel 33. By reason of the connections 43 between the tabs 39 and elements 34, this'movement of the side wall elements raises the connected ends of the tabs slightly above the plane of the bottom panel 33, as shown in Figure 5. Since the tabs 39 are to be swung inwardly over the bottom panel 33 to engage in the slits 44, it will be clear that this raising of the tabs automatically upon folding of the elements 34 facilitates setting up of the container. If desired, however, the connection 43 may be omitted, since the tabs may be raised independently of the side wall elements to the proper position. After the side wall elements 34 have been moved to erected position, the end wall panels 35 are swung upwardly about the lines 32 into perpendicular relation with the bottom panel 33, the end wall elements 31 at the same time being bent about the lines 38. The elements 31 are then swung about the lines 36 into position substantially in the vertical planes of the lines 3|, the tabs 39 at the same time moving inwardly to engage over the bottom and in the slits 44. The connections 43 readily rupture upon the inward movement of the tabs. The engagement of the notches with the closed end of the slits 44 and of the slits 44 with the tabs is substantially the same as that of the corresponding elements in the form of the invention illustrated in-Figures 1 to 3. The final position of the parts in the erected condition of the box is illustrated in Figure 6. Of course, the order of folding may vary from that just described. I

It will be seen that the end wall elements 31 are of such size and shape that they overlap the adjacent ends of the side wall panels 34, thus providing side walls for the container. It is because the elements 31 have the inner surfaces lying against the outer surfaces of the elements 34 that the lines 36 may be offset outwardly of the lines 3| in the blank, as described above, and the lines 33 similarly may be offset outwardly of the lines 32 to permit the tabs 39 to lie fiat against the bottom panel. The side wall elements in the container shown in Figure 6 are of somewhat greater height than the end walls 35 and end wall elements 31, although it will be obvious that this relationship is not necessary to the invention. This form of the invention is cover for the form of container shown in Figures 1 to 3. With the locking tabs positioned against the bottom panel 33, which when the container is employed as a cover becomes a top or cover panel, there is no interference from the tabs and associated locking elements when this construction is telescoped over the container of Figure 3, as might be the case if both the container and cover were constructed in accordance with the first form of the invention. The projection of the side wall elements 34 beyond the end walls also facilitates initial disposition of this second form of the container in telescoping relation with the first form. It is expressly pointed out, however, that this form of the container is not by any means limited to use as a cover, since it constitutes a container well adapted for many uses. As with the first form of container described above, cover flaps of any suitable type may be provided on any of the walls or wall elements of this form of container.

Although the form of container illustrated in Figure 6 may at first glance appear to be quite different from that illustrated in Figure 3, essentially the construction is the same in both cases. If the container of Figure 6 be visualized as standing on end wall panel 35, it will readily be apparent that the corner-forming parts of this container correspond substantially to the several parts of the container of Figure 3, and are disposed in substantially the same relation, so

far as the corner locking arrangement is concerned. Thus, the end wall 35 corresponds to the bottom panel |3 of the previously described form, the end wall element 31 corresponds to the end wall IS, the tab 39 to the tab H, the bottom panel 33 to the side wall l4, and the side wall element 34 to the end flap l8.

In Figures 7 and 8, the invention is illustrated as embodied in a tray suitable for packaging tomatoes and other products which is generally similar to the container illustrated in Figure 3.

The blank 50 as shown in Figure '7 comprises a suitable sheet with longitudinal parallel score lines 5| and transverse parallel score lines 52 defining a substantially rectangular bottom panel 53. Side wall panels 54 and end wall panels 55 are connected to the bottom panel along the lines 5| and 52, respectively. End cover flaps 56 are hingedly connected to the end wall panels 55 along hinge lines 51, although these cover flaps may be omitted if desired. Locking tabs 58 are hinged on the end edges of the end wall panels 65 along lines 59. These hinge lines 59 extend at substantially right angles to the lines 52, and are offset inwardly relative to the lines 5| a distance substantially equal to twice the thickness of the material employed for the blank. The tab 58 is divided from the side wall panel 54 by a cut 60, substantially aligned with the line 52. The ends of this out preferably are curved to extend inwardly relative to the line 52 a distance substantially equal to one thickness of the material. A cut 6|, preferably aligned with the line 5|, extends from the margin of the blank to the outer end of the tab 58, and a notching cut 62 extends from the inner end of the cut 6| to the outer end of the hinge line 59. This cut 62 serves to provide a notch in the tab when the blank is folded on the line 59.

An end flap 63 is hinged to a portion of the adjacent end edge of the side wall panel 54 along a line 64, a portion of the edge of the flap 63 in alignment with the line 64 being separated from auvaav'e an adjacent portion of this edge of the panel 54 by a slit 65. The slit 55 extends outwardly from the outer end of the cut 60 to the inner end of the hinge line 64, and both the slit 55 and line 54 are ofiset inwardly of the line 52 a distance corresponding to the thickness of the material. The cut 6| separates the flaps 55 from the end wall panel 55, and a cut 66 extends from the junction of the cuts and 62 to the cut 50 to separate the flap 63 from the tab 58. As in the two previously described forms, the cut 66 is arcuate, but may be straight or otherwise curved, if desired. The dimension of the tab 58 along the cut 50 is smaller than the perpendicular distance from the line 52 o! the end of the tab defined by the junction of the lines 62 and 6B, and the closed outer end of the slit 55 is at a point spaced perpendicularly from the hinge line 59 a distance no greater, and preferably less, than the distance from the line 52 of the tab end defined by the lines 62 and 56.

A slit 51 is provided in each end wall panel 55 along a line corresponding to the upper edges of the pair of flaps 53 at each end when the blank is erected in container form. As illustrated, this slit 6'! is in the shape of a shallow V, since the flaps are shown as so cut that when erected their upper edges will incline downwardly and inwardly from the side walls.

One end of the container formed from the blank of Figure 7 is shown in Figure 8, the steps of erecting the blank into container form being substantially the same as explained above in connection with the construction of Figures 1 to 3. A notch 58 is provided in each tab 58 by the cut 62 upon folding of the tab on the line 59, this notch engaging with the inner end of the hinge line 64, and the adjacent end portion of the tab engaging in the slit 65. The upper edge of the slit 6'! provides a lip which is deflected inwardly of the container for irictionally engaging the upper edges of the end flaps 53, thus providing additional means for maintaining the flaps in I their abutting relation. Instead of the slit 61 being located in the end wall to engage the upper edges of the flaps 63, it could be provided at the bottom of the end wall and the flaps so formed that portions thereof would extend into the slit to be irictionally retained in position thereby. After the container has been erected as shown in Figure 8, it may be filled with tomatoes or other items and the flap 56 bent inwardly on the line 51 to a substantially horizontal position. A sheet of transparent material may then be used to cover the top of the container. or course, other covering means may be employed, or no cover provided, as desired.

When the container is set up, the oilsetting of the hinge lines 64 of the end flaps inwardly relative to the cut 60 by one thickness of the material permits the end flaps 63 to lie against the inner surface of the end walls 55 without bending or distortion thereof, and positions the edge portion of the side wall 54 defined by the cut 60 in the plane of the outer surface of the end wall 55. A similar result would be achieved as to the locking tabs 58 by offsetting the tab hinge lines 59 a distance equal to one thickness of the paperboard inwardly of the cut GI and lines 5|. For greater ease of insertion of the tabs into the interior of the container and into engagement with the slits 55, however, these hinge lines 59 are preferably offset by twice the thickness of the material. This also allows for spreading of the material at the trihedral corners or the container resulting from bending of the adjacent members. Although the double thickness ofiset theoretically prevents an absolutely square corner, as a practical matter a square corner is provided because, while the upper portion or the end of the side wall may be held somewhat inwardly of the bottom portion, the bottom portion is in the vertical line of the edge portion or the end wall defined by the cut 6!.

Oflsetting of the lines and cuts, or certain of them, in the forms of container shown in Figures 3 and 6 may be utilized in the same way as in the form of Figure 8, as already indicated above. The ofisetting in any case may be varied as rendered necessary or desirable by the characteristics of the particular paperboard employed.

Although the container in each of the forms illustrated is shown as provided with a notch in the locking tab for maintaining the tab in locked relation with the other parts of the container, under some conditions and for certain purposes other means may be employed for maintaining the tab in looking relation with the associated slit. For example, the frictional engagement between the tab and the edge portions defining the slit may be used to hold the tab in position, particularly where the container is to be overwrapped with cellophane or the like. In such case, the overwrapping material, once it is applied, serves 'as a means for maintaining the tab in position. Again, if the paperboard mate rial is relatively compressible, as in the case of corrugated board, retention of the tab in the slit may be achieved solely by its frictional engagement therein. If the slit is so utilized to hold the tab by friction alone, the slit performs a double function in holding both wall members against moving out or their erected positions.

The lock tab may be formed much smaller than as shown, if desired, so as to extend from only an intermediate portion of the edge of the element to which it is hinged. The construction illustrated in each embodiment of the invention, however, provides a stronger corner for the container and is, therefore, preferred.

Although the terms side wall" and "end wall" have been used in describing the embodiments of the invention, it will be clear that although the container in each modification is illustrated as having a rectangular bottom, and the walls as being disposed perpendicular to this bottom, the invention is applicable to other shapes of containers. For example, a six-sided container might be provided employing the corner lock construction of this invention, and similarly, a container employing this lock construction might be provided with the side walls at an angle to the bottom other than a right angle. Such adaptations of the invention to containers of various shapes will be obvious to those skilled in the art, and are clearly within the purview of this invention.

It will be obvious that various changes and modifications in the structure illustrated and described may be made without departing from the principles of the invention. Some of these possible changes and modifications have been pointed out in the foregoing description, and others will readily suggest themselves to those skilled in the art. In view of the variations which may be made in the structure employed to embody the invention, it is not intended to limit the invention to the specific embodiments illustrated and described, but only as required by the spirit and .scope or the appended claims.

The form of my invention shown in Figures 7 and 8 hereof is included in my divisional application, Serial No. 137,190, filed January 6, 1950.

I claim:

1. A blank for a paperboard container comprising a paperboard sheet cut and scored to provide a rectangular bottom panel, an end wall panel hingedly connected along a fold line to an end edge of said bottom panel, a side wall panel hingedly connected along a fold line to a side edge of said bottom panel, a tab hingedly connected to a portion of a side edge of said end wall panel along a fold line offset inwardly out of alignment with said side wall panel fold line, the remaining portion of said side edge of said end wall panel being in alignment with the side wall panel fold line, and a flap hingedly connected along a fold line to a portion of an end edge of said side wall panel and separated therefrom along an adjacent portion of said end edge of said side wall panel defining therewith a slit opening toward said bottom and end wall panels, said end wall panel having a cut extending from the inner end of the last named edge portion of its side edge inwardly tosaid tab fold line at a point thereof remote from said bottom panel and providing a notch at the upper edge of said tab disposed and adapted for locking engagement with said flap at the closed end of said slit, when said blank is folded into container form with said tab folded on its hinge line.

2. A blank for a paperboard container comprising a paperboard sheet cut and scored to provide a rectangular bottom panel, an end wall panel hingedly connected along a fold lineto an and edge of said bottom panel, a side wall panel hingedly connected along a fold line to a side edge of said bottom panel, a tab hingedly connected to a portion of a side edge of said end wall panel along a fold line offset inwardly out of alignment with said side wall panel fold line and having one edge separated from a portion of the adjacent end edge of said side wall panel and a portion of said end edge of said bottom panel by a cut aligned with said end wall panel fold line, the remaining portion of said side edge of said end wall panel being in alignment with end thereof and providing a notch at the upper edge of said tab, said one edge of said tab being disposed to seat on said bottom panel and said notch being disposed and adapted for locking engagement with said flap at the outer end of said slit, when said blank is folded into container form with said tab folded on its hinge line.

3. A blank for a paperboard container comprising a paperboard sheet cut and scored to provide a rectangular bottom panel, an end wall panel hingedly connected along a fold line to an end edge of said bottom panel, a side wall panel hingedly connected along a fold line to a side edge'of said bottom. panel, a tab hingedly connected to a portion of a side edge of said end wall panel along a fold line offset inwardly out of alignment with said side wall panel fold line and having one edge separated from a portion of the adjacent end edge of said side wall panel and a portion of said end edge of said bottom panel by a cut aligned with said end wall panel fold line, the remaining portion of said side edge of said end wall panel being in alignment with the side wall panel fold line, a flap separated for a portion of its width from said side wall panel by a slit constituting an outward extension of said out and hingedly connected to a portion of said end edge of said side wall panel along a fold line extending outward from said slit, said flap being otherwise free from said side wall panel and being free from said end wall panel, the latter panel having a cut extending from its side edge inwardly to said tab fold line at the outer end thereof and providing a notch at the upper edge of said tab, said one edge of said tab being disposed to seat on said bottom panel and said notch being disposed and adapted for locking engagement with said flap at the outer end of said slit, when said blank is folded into container form with said tab folded on its hinge line.

RALPH E. ACKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,132,466 Gamble Mar. 16, 1915 1,470,141 Bryson Oct. 9, 1923 1,649,452 De Clerco Nov. 15, 1927 1,842,237 Becker Jan. 19, 1932 2,089,509 Taylor Aug. 10, 1937 2,445,034 Moore July 13, 1948 

